Automated replacement of transmission fluid

ABSTRACT

Apparatus and method of replacing old fluid in a transmission system by feeding clean fluid into the system from a clean fluid tank using a pump and draining the old fluid into a waste tank and using a processor to monitor the clean fluid pressure in the clean tank and the old fluid pressure in the waste tank and adjusting the pump&#39;s speed using the processor such that the old fluid is drained at substantially the same rate as the clean fluid is fed.

This application is a continuation of application Ser. No. 09/184,621,now U.S. Pat. No. 6,062,275, filed on Nov. 2, 1998, the disclosure ofwhich is incorporated fully herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to vehicular maintenance and,more particularly, to systems and methods for replacing transmissionfluid.

For the past several years, substantial attention has been directed tothe field of transmission fluid changers. Such systems are useful, forexample, in draining the oil from a vehicle transmission system in orderto replace the transmission filter and/or to completely replace the oldtransmission fluid with new fluid. Existing transmission fluid changerssuch as those described in U.S. Pat. Nos. 5,447,184, 5,472,064,5,318,080 and 5,370,160 require substantial human intervention duringthe fluid exchange process.

However, there is an intense need within the industry to provide a moreefficient, less time consuming and a more user-friendly system fortransmission fluid replacement that substantially reduces humanintervention.

In view of this necessity, it is believed that those skilled in the artwould find automated systems and methods for draining, filling andchanging of transmission fluid to be quite useful.

SUMMARY OF THE INVENTION

In a first separate aspect, the present invention is directed to anapparatus for replacing waste fluid with clean fluid. The apparatusincludes a waste tank for receiving the waste fluid from a first port, aclean tank containing the clean fluid, a processor coupled to first andsecond sensors, and a pump coupled to the processor for pumping theclean fluid into a second port. The processor measures the waste fluidlevel via the first sensor and measures the clean fluid level via thesecond sensor. Based on these measurements, the processor controls thepump's speed.

In a second separate aspect, the apparatus of the first separate aspectmay also include a solenoid switch that includes first and second portsand a plurality of paths for transferring the clean and waste fluids.

In a third separate aspect of the invention, the paths in the solenoidswitch of the second separate aspect may be selected via the processorby measuring the fluid pressure at each solenoid switch port.

In a fourth separate aspect, the apparatus of the first separate aspectmay also include a disposal pump coupled to the processor for pumpingthe waste fluid from the waste tank into a disposal tank.

In a fifth separate aspect, the present invention is directed to amethod of replacing waste fluid with clean fluid. The method comprisesthe step of providing a waste tank for receiving the waste fluid from afirst port and a clean tank containing the clean fluid. The methodfurther includes the step of coupling a processor to a first sensor, asecond sensor and a pump for pumping the clean fluid into a second port.The method also includes the steps of measuring the waste fluid via thefirst sensor using the processor and measuring the clean fluid via thesecond sensor using the processor. And the method includes the step ofcontrolling the pump using the processor based on the measuring steps.

In a sixth separate aspect, the present invention is directed to amethod of replacing waste fluid in a system with clean fluid. The methodincludes the steps of draining a portion of the waste fluid from thesystem into a waste tank, measuring the amount of the drained fluid witha processor, and replacing the drained fluid with clean fluid from aclean tank using a pump that is controlled by the processor.

In a seventh separate aspect, the method of the sixth separate aspectmay include the steps of withdrawing the remaining portion of the wastefluid plus the clean fluid in the system into the waste tank, gaugingthe amount of the withdrawn fluid using the processor, feeding thesystem with the clean fluid using the pump, gauging the amount of fluidin the feeding step using the processor, and controlling the pump suchthat the withdrawing step proceeds at substantially the same rate as thefeeding step.

In an eighth separate aspect, the method of the seventh separate aspectmay include the step of terminating the process when the clean fluidreaches a low level in the clean tank.

In a ninth separate aspect, the method of the seventh separate aspectmay include the step of pumping an extra amount of the clean fluid intothe system.

Accordingly, it is an object of the present invention to provideapparatus and method of replacing one fluid with another in a system,such as a vehicle transmission system.

Other objects and features of the present invention will become apparentfrom consideration of the following description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an automated system for replacingtransmission fluid;

FIG. 1A is an exploded view of a solenoid switch of the system of FIG.1;

FIG. 2 is a pictorial view of a control panel of the system of FIG. 1;and

FIG. 3 is a pictorial view of the system of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Turning now to the drawings, FIG. 1 provides a schematic illustration ofa fluid changer system 100 according to a preferred embodiment of thepresent invention. As shown, the system 100 includes a clean fluid tank110, a waste fluid tank 120, a clean pump 130, a waste pump 140, asolenoid switch 160, a disposal tank 170 and a printed circuit board(PCB) 150 with an on-board microprocessor (not shown), a clean tankpressure sensor 151 and a waste tank pressure sensor 152.

The clean tank 110 contains fresh fluid that is supplied to a vehicletransmission system (not shown). The clean tank 110 also includes aclean tank tube 112 with one end inside the clean tank 110 and the otherend extending out and being connected to a clean fluid pump 130. Asshown, the clean tank tube 112 includes a filter 116 for purifying thefresh fluid before reaching the clean pump 130.

The clean pump 130 pumps the fresh fluid out of the clean tank 110through the clean tank tube 112 and filter 116 into the clean pumpoutlet tube 132. The clean pump outlet tube 132 transports the fresh andpurified fluid to the solenoid switch 160, the operation of which isdiscussed below.

Turning back to the clean tank 110, the clean tank 110 further includesa port 115 for withdrawing fluid from or adding fluid to the clean tank110. The clean tank 110 also includes a clean sensor tube 114 thatextends out of the tank 110 and is coupled to the PCB 150, so theon-board microprocessor can measure the fresh fluid pressure in theclean tank 110.

As illustrated, the PCB 150 also receives a waste sensor tube 124 fromthe waste tank 120 for the purpose of measuring the waste fluid pressurein the waste tank 120. The waste tank 120 also includes a waste tanktube 122 which extends out of the waste tank 120 and a waste filter 126to reach a waste pump 140 for pumping out the waste fluid. The wastefluid is passed through the filter 126 so to prevent the impurities ofthe waste fluid from interfering with the proper operation of the wastepump 140.

As seen in FIG. 1, the waste pump 140 pumps the waste fluid out via thewaste tube 122 and pumps the waste fluid into the disposal tank 170 viaa disposal tube 145.

Referring back to the waste tank 120, the waste tank 120 receives thewaste fluid through a waste inlet port 127 connected via a waste inlettube 128 to the solenoid switch 160.

In a preferred embodiment, the solenoid system 160 comprises threesolenoid valves (not shown) that are controlled via the PCB 150microprocessor in accordance with the modes of operation describedbelow. The three solenoid valves are set or reset according to each modeof operation to create the desirable fluid paths, such as fluid paths161, 163, 165, 166 and 167, as shown in FIG. 1A.

In addition to the clean pump outlet tube 132 and the waste inlet tube128, the solenoid switch 160 is also connected to a first hose 162 and asecond hose 164 for receiving the waste fluid from the vehicle andreplacing the waste fluid with fresh fluid from the clean tank 110.Connected to the first hose 162 is a first hose pressure sensor 168 thatis electrically connected to the PCB 150 via the first sensor wire 154.Similarly, connected to the second hose 164 is a second hose pressuresensor 169 that is electrically connected to the PCB 150 via the secondsensor wire 153.

In a preferred embodiment, the cooler line (not shown) of the vehicle isdisconnected and reconnected at one end through the first hose 162 andat the other end through the second hose 164. For example, when therecirculating path 167 is established within the solenoid system 160,the transmission fluid may flow from one end of the cooler line throughthe first hose 162 through the recirculating path 167 and the secondhose 164 to reach the other end of the cooler line. While the vehicleengine is operating, the vehicle transmission pump (not shown) pumps thetransmission fluid through the cooler line. The transmission fluid,depending upon the fluid flow direction, enters either from the firsthose 162 or the second hose 164. Regardless of the fluid direction,however, the vehicle's transmission fluid circulates through the path167 and back to the vehicle system.

To utilize the system 100 for replacing the waste fluid, the vehiclecooler line is disconnected while the vehicle's engine is off. Thecooler line is connected to the first hose 162 at one end and the secondhose 164 at the other end. At this point, the system 100 is powered on.The default setting for the solenoid system is the recirculating path167. Accordingly, when the vehicle engine starts, the transmission fluidis pumped through the solenoid system 160.

Now, referring to FIG. 2, a computer control panel 200 of a preferredembodiment is shown. In a preferred method of replacing the waste fluid,the process may begin by pressing the drain button 220. The drain panfunction drains the waste fluid from the vehicle so the vehicletransmission pan (not shown) can be dropped in order to change thetransmission filter (not shown).

By pressing the drain button 220, the on-broad microprocessor begins theprocess by turning on the drain LED 222 to indicate that the drainprocess has begun. If the vehicle's engine is off, the on/start LED 212blinks to indicate that the engine must be turned on so the vehicle'stransmission pump starts pumping the waste fluid through the solenoidsystem 160. Once the engine is turned on, the on/start LED 212 stopsblinking and stays on continuously.

At this point, the on-board microprocessor determines the transmissionfluid direction in the first and second hoses 162 and 164 in order toset up the solenoid valves and select the proper path inside thesolenoid system 160. This task is accomplished by sensing the fluid flowin the first and second hoses 162 and 164 via their respective pressuresensors 168 and 169. According to the sensed pressures, themicroprocessor determines the waste fluid circulation direction in thecooler line. Also, based upon the pressures sensed from the pressuresensor tubes 114 and 124, the microprocessor determines the amount offluid in each tank. The waste tank 120 being substantially empty has alower fluid pressure than the clean fluid tank 110 containing freshfluid to be pumped in.

Having determined the fluid flow direction and the location of the tanks110 and 120, the solenoid valves are set such that the proper path istaken. For example, if the fluid enters the solenoid system 160 throughthe first hose 162, the path 161 is set up such the waste fluid isdirected into to the waste tank 120 through the waste inlet tube 128through the waste inlet port 127. On the other hand, if the fluid flowdirection is from the second hose 164, the solenoid switch is set upsuch that the path 166 is selected.

Before directing the waste fluid to the waste tank 120, using thepressure sensor 152 the present fluid level of the waste tank 120 iscaptured by the microprocessor for future determination of the amount ofdrained waste fluid. In a preferred embodiment, the fluid pressure inthe waste tank 120 is checked every seven seconds to determine whetherthe waste fluid is flowing and whether the waste tank 120 is beingfilled. If the waste tank 120 is not being filled, the drain LED 222goes off, the solenoid switch valves are set to assume the recirculatepath 167, the engine off/stop LED 214 turns on, the engine on/start LED212 flashes, and the sounder sounds until the stop button 270 ispressed.

However, if these error conditions do not occur, the transmission fluidis sufficiently drained so the vehicle's transmission pan (not shown)can be dropped. The solenoid valves are set such that no more fluidflows from the first and second hoses 162 and 164, and the low vehiclefluid LED 224 is turned to indicate that the drain process is complete.

At this step, the vehicle transmission pan may be dropped and thetransmission filter may be changed without transmission fluid flowingfrom the transmission system. After the filter has been replaced and thedrain pan is placed in its original position, the drained waste fluidmay be replaced by pressing the fill button 240 on the control panel200.

At the fill step, the PCB 150 determines the volume of the drained wastefluid based on the captured fluid level in the waste tank 120 at thestart of the drain process and the current fluid level in the waste tank120. Those of ordinary skill recognize that the fluid level may becalculated based on the sensed pressure via the pressure sensor 152.Knowing the drained volume, the PCB 150 activates the clean fluid pump130 to pump an equal volume of fresh liquid from the clean fluid tank110 to the transmission system. In other words, enough clean fluid ispumped out such that pressure sensors 151 and 152 reach the samepressure balance as before the drain process started.

The PCB 150 also sets up the solenoid valves such that the fluid carriedvia the clean pump outlet tube 132 is routed correctly. If the firsthose 162 was determined to be the in-hose—as determined at the beginningof the draining process—the solenoid system 160 is set up to select path165 so the clean fluid reaches the first hose 162 and from there intothe transmission. On the other hand, if the second hose 164 is thein-hose, the path 163 is taken so the clean fluid reaches the secondhose 164.

When the fill button 240 is pressed, the fill indicator LED 242 goes onindicating that a fill process is in progress. If the fill button 240 ispressed only once, an amount equal to the drained fluid volume is pumpedback into the transmission system. However, each additional time thatthe fill button 240 is pressed the system is instructed to pump an extrahalf a quart of fluid into the transmission system.

Accordingly, if the fill button 240 is pressed twice instead of once,the +½ LED in box 246 comes on indicating that an extra half a quartwill be pumped into the transmission system. If the fill button 240 ispressed three times, the +1 LED in box 246 comes and one extra quart ispumped in. If the fill button is pressed eight times, the three LEDs +½,+1 and +2 in box 246 come on and 3.5 extra quarts of fluid will bepumped in. The fill indicator LED 242 goes off when the fill process iscomplete.

The next step of the process may begin by pressing the change fluidbutton 230 on the control panel 200. At this step, the system 100 pumpsclean fluid into the vehicle at substantially the same rate as pumpingwaste fluid out of the transmission system. Before the change fluidbutton 230 is pressed the first and second hoses 162 and 164 must beconnected to the cooler line of the vehicle. The solenoid system is inits default state, i.e., the recirculation path 167 is in effect.

Once the change fluid button 230 is pressed, the change fluid processstarts. If the clean fluid level in the clean tank 110 is low, the lowclean fluid LED 244 starts flashing and the sounder starts soundinguntil the stop button 270 is pressed. Also, if the waste tank 120 isover ¼ full, the empty waste LED 260 starts flashing and the soundersounds until the stop button 270 is pressed. If the preliminaryconditions are correct, the fluid levels in the clean tank 110 and thewaste tank 120 are measured via the pressure sensors 151 and 152,respectively. In case the low clean fluid LED 244 is on, the clean fluidtank must be filled.

According to the flow direction-sensing process explained above, thesystem 100 determines the in-hose and the out-hose directions betweenthe first and second hoses 162 and 164, and also determines the cleanpump outlet tube 132 and the waste inlet tube 128 via pressure sensors168, 169, 151 and 152, respectively. Once the flow direction isdetermined the solenoid valves in the solenoid system 160 are properlyset to pump in the clean fluid and receive the waste fluid. For example,if the second hose 164 is the out-hose, path 163 is selected so thatclean fluid flows from the clean fluid outlet tube 132 to the secondhose 164 and into the transmission system. In this case, path 161 isalso selected so the waste fluid being pumped by the vehicle engineflows from the first hose 162 through path 161 into the waste inlet tube128 and the waste inlet port 127.

However, if the first hose 162 is the out-hose, path 165 is selected sothe clean fluid flows from the clean fluid outlet tube 132 into thefirst hose 162 and into the transmission system. Naturally, path 166 isalso selected so the waste fluid flows from the second hose 164 to thewaste inlet tube 128 and into the waste tank 120.

Once the proper paths are selected, the clean fluid pump 130 pumps outclean fluid from the clean fluid tank 110 via the clean fluid tube 112and through the clean fluid filter 116. From there, clean fluid ispumped through the clean pump outlet tube 132 into the solenoid switch160 and into the transmission system through the pre-selected path. Asfor the waste fluid, the vehicle transmission pump (not shown) alsopumps the transmission fluid as the engine is running. Waste fluid flowsfrom either the first hose 162 or the second hose 164 and takes thepre-selected path to reach the waste inlet tube 128 and the waste tank120.

In a preferred embodiment, every seven seconds during the change fluidprocess, the microprocessor on the PCB 150 monitors the flow rate basedon pressure values obtained from the waste tank pressure sensor 152 andthe clean tank pressure sensor 151. The change in pressure in the cleantank 110 is calculated by simply subtracting the current pressure fromprevious pressure. The change in pressure in the waste tank 120 iscalculated by subtracting the previous pressure from the currentpressure.

If the change in pressure in the waste tank 120 is higher than thechange in pressure in the clean tank 110, it means that the waste tank120 is being filled more quickly than the clean tank 110 is beingemptied. In that case, the clean pump's 130 speed must be increased by avalue proportionate to the difference in pressure changes in the cleantank 110 and the waste tank 120.

However, if the change in pressure in the clean tank 110 is higher thanthe change in pressure in the waste tank 120, it means that the wastetank 120 is being filled less rapidly than the clean tank 110 is beingemptied. Accordingly, the clean pump's 130 speed must be reduced by avalue proportionate to the difference in pressure changes in the cleantank 110 and the waste tank 120.

The automatic flow rate control and its timing are important featuressince pumping the clean fluid faster than the vehicle's transmissionpump is pumping the waste fluid will cause a fluid overflow in thetransmission system. On the other hand, slow pumping of the clean fluidwould cause a fluid underflow in the transmission system which maydamage the vehicle and would also require the vehicle's engine bestopped from time to time to allow the clean tank pump 130 to catch upwith the vehicle's transmission pump's faster speed. Therefore, those ofordinary skill in the art would appreciate such properly timed flowcontrol that substantially eliminates human intervention during thechange fluid process.

If the clean tank 110 becomes empty during the fluid change process, thesounder starts sounding and the solenoid system 160 reverts back to itsdefault recirculating path 167. In such event, more fluid may be addedto the clean fluid tank 110 providing the waste tank level is below ¼tank full and the change fluid button 230 may be pressed so the system100 restarts the process from the last point. If LED 162 is lit, wastefluid must be emptied before proceeding.

In a preferred embodiment, once the fluid level in the clean fluid tank110 reaches the low-level line 111, the change process is complete andthe complete LED 252 comes on to indicate the end of process. At thecompletion of the fluid change process, the solenoid system reverts toits default recirculating path 167 and the transmission fluid circulatesthrough the solenoid switch.

At this point, the system 100 may be used to add extra fluid to thetransmission system by pressing the fill button 240, as explained above.

At the final stage, the vehicle engine is stopped and the cooler line isdisconnected from the first and second hoses 162 and 164 and reconnectedin its original form. Pressing the empty waste button 260 on the controlpanel 200 may also empty the waste tank 120.

Once the empty waste button 260 is pressed, the empty waste LED 262comes on indicating that the waste tank 120 is being emptied out intothe disposal tank 170. The waste fluid is pumped out the waste tank 120using the waste fluid pump 140 and via the waste fluid tube 122, throughthe waste fluid filter 126 and from there to the disposal tube 145 andthe disposal tank 170. Once the waste tank 120 is emptied, the emptywaste LED 262 turns off. The process may also be stopped at any time bypressing the stop button 270.

Turning to FIG. 3, a pictorial representation of a transmission servicesystem 10 is shown. As shown, the service system 10 includes the fluidchanger system 100 and the control panel 200. In addition, the servicesystem includes a fluid port 12 corresponding to the clean tank port 115for adding or draining fresh fluid. The service system 10 also includesa clean fluid level meter 16 and a waste fluid level meter 14 forvisually determining the fluid level in the clean fluid tank 110 and thewaste fluid tank 120, respectively.

Those skilled in the art will appreciate that, while the system 100provides for processes such as draining, filling, changing fluid andemptying waste fluid, it would be possible in accordance with thepresent invention to design a system that allows for only one or more ofthe above-described processes.

While the present invention is susceptible to various modifications andalternative forms, specific examples thereof have been shown in thedrawings and are herein described in detail. It should be understood,however, that the invention is not to be limited to the particular formsor methods disclosed, but to the contrary, the invention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the appended claims.

What is claimed is:
 1. A fluid exchange apparatus comprising: a firsttank, said first tank being adapted to store a first fluid; a firstport, said first port being coupled to said first tank; a second tank,said second tank being adapted to receive a second fluid; a second port,said second port being coupled to said second tank; and a switchingapparatus having a plurality of switch ports, said switching apparatusbeing coupled to said first port and being coupled to said second port;wherein said switching apparatus is capable of selectively connectingsaid first port to any one of said plurality of switch ports, andwherein said switching apparatus is capable of selectively connectingsaid second port to any one of said plurality of switch ports.
 2. Theapparatus of claim 1 further comprising a first pump, said first pumpbeing coupled to said first port and being coupled to said first tank,wherein said first pump is adapted to pump said first fluid from saidfirst tank and into said first port.
 3. The apparatus of claim 2 furthercomprising a processor, said processor being coupled to a first sensorand a second sensor and being capable of controlling said pump.
 4. Theapparatus of claim 3 wherein said processor makes a first measurementwith said first sensor, makes a second measurement with said secondsensor, and controls said pump based upon said first and said secondmeasurements.
 5. The apparatus of claim 2 wherein said pump includes afilter.
 6. The apparatus of claim 1 further comprising a second pump,said second pump being coupled to both said second port and said secondtank, wherein said second pump is adapted to pump said second fluid fromsaid second port and into said second tank.
 7. A method of exchangingfluid within a contained area, said method comprising the steps of:providing a switching apparatus having a plurality of switch ports;coupling said switching apparatus to a first port and a second port;providing a first tank for storing a first fluid; providing a pump forpumping said first fluid out of said first tank and into said firstport; providing a second tank for receiving a second fluid from saidsecond port; connecting said first port selectively to any one of saidplurality of switch ports using said switching apparatus; and connectingsaid second port selectively to any one of said plurality of switchports using said switching apparatus.
 8. The method of claim 7 furthercomprising the steps of coupling a processor to a first sensor, a secondsensor, and said pump and using said processor to control said switchingapparatus.
 9. The method of claim 8 further comprising the step ofmeasuring said first fluid with said first sensor and delivering asignal indication of said measurement to said processor.
 10. The methodof claim 8 further comprising the step of measuring said second fluidwith said second sensor and delivering a signal indication of saidmeasurement to said processor.
 11. The method of claim 8 furthercomprising the step of controlling said pump based on said measuringsteps using said processor.